Diffusion/filtration devices are used for various kinds of medical treatments, such as hemodialysis, hemofiltration, plasmapheresis and immunotherapy. Other fields of use include, inter alia, dialysis in general and filtration in general, for example in connection with the cleaning or desalination of sea water.
During the production of such diffusion/filtration devices each end of the housing, with a bundle of fibers therein, is normally enclosed in a casting mould into which the potting material for the adjacent end walls is fed in a liquid condition penetrating into and around the fibers. The penetration is controlled by the casting so that the penetration into the fibers is less than that around the fibers, making it possible to open the ends of the fibers by making a cut between the respective penetration depths.
These penetration depths may be controlled in different ways. Preferably, though, it is controlled in accordance with the method described and claimed in EP-B-O 165 478. Thus, the wall material may be fed into the device as described in the above European patent or, in the alternative, through the other two normally existing inlets/outlets as described in U.S. Pat. Nos. 4,227,295 or 4,329,229. In both cases, though, the wall material is firmly attached to the inside wall of the housing.
As a result, during the curing of the wall material, stresses develop which sometimes result in unacceptable cracks in the wall or the housing. Such cracks may for instance be created in connection with the opening of the fiber ends, the flushing of the apparatus or the sterilization of the completed apparatus.
An attempt to solve the above problem is described and claimed in U.S. Pat. No. 4,334,993. The present invention provides an alternative and novel solution for the same problem. Furthermore, the present invention provides additional advantages as described below.